1. Field of the Invention
This invention relates to a tensioner for an endless power transmission belt which provides both belt tensioning and dampening.
2. Prior Art Statement
In the art of transmitting power employing an endless polymeric power transmission belt, such as driving or rotating driven sheaves of a plurality of automobile accessories using a belt which is driven by a driving sheave connected to the automobile engine crankshaft, it is difficult to maintain such belt under tension required to assure non-slipping engagement and driving of the driven sheaves; and, numerous belt tensioners have been proposed and used heretofore in an effort to provide the required tension. Especially where one of the accessories being driven is the compressor of an air conditioning system for the automobile, such compressor upon being driven creates a tight side and a slack side in the belt on opposite sides of the compressor sheave. The tight side has a varying tightness of a cyclic character as a function of the inherent cyclic change in the load imposed by the compressor. It is a problem to provide the required tension in the overall belt as well as prevent any tendency of the belt to oscillate in an undesirable manner as a result of this cyclic load change.
It is known in the art to provide a tensioner for an endless power transmission belt wherein the belt is employed in driving a sheave comprising at least one accessory which upon being driven creates a slack side and a tight side in the belt on opposite sides of the sheave and the tensioner comprises, a first support arm having pivot means, a first idler pulley rotatably carried by the arm, and a pivot pin extending through the pivot means and pivotally supporting the arm adjacent the sheave with the first pulley engaging the slack side to enable tensioning thereof and in a similar manner as disclosed in U.S. Pat. No. 3,142,193.
It is also known to utilize a pair of pulleys as a portion of a tensioner wherein such pair of pulleys are suitably disposed along the length of a belt to provide tensioning thereof and as disclosed in U.S. Pat. No. 1,578,700.
It is an object of this invention to provide an improved tensioner for an endless power transmission belt.
Another object of this invention is to provide an improved tensioner that also provides dampening of the belt and thereby assures smooth running thereof free of vibration and/or oscillation.
Other aspects, embodiments, objects, and advantages of this invention will become apparent from the following specification, claims, and drawings.